1. Field of the Invention
The present invention relates to a light emitting diode operated by being directly connected to an AC power source, and more particularly, to an AC light emitting diode having improved performance such as quantum efficiency.
2. Description of the Related Art
A light emitting diode (LED), which is a photoelectric conversion device having a structure in which an N-type semiconductor and a P-type semiconductor are joined together, emits predetermined light through recombination of the electrons and holes. Such an LED is widely used for display elements and backlights. Further, LEDs have less electric power consumption and a longer lifespan as compared with conventional light bulbs or fluorescent lamps, so that their application areas have been expanded to the use thereof for general illumination while substituting for conventional incandescent bulbs and fluorescent lamps.
An LED is repeatedly turned on/off depending on the direction of current under an AC power source. Therefore, when the LED is directly connected to an AC power source, the LED may not continuously emit light and may be easily damaged due to reverse current. Also, the LED cannot be used to be directly connected to a general AC power source.
In order to solve such a problem, there may be used a method of operating an LED by disposing a rectifier between the LED and an AC power source and rectifying AC to DC. However, the necessity of such a rectifier makes it difficult to substitute LEDs for illuminators such as fluorescent lamps. Alternatively, there may be used a method of connecting a plurality of LEDs in reverse parallel with one another to be directly connected to a high-voltage AC power source. However, there are problems in that since a large number of LEDs should be connected to be operated, the entire size of a light emitting apparatus may be large and the number of processes such as wire connection may be increased as the respective LEDs are connected to one another.